I agree with above.
The real word difference in speed between SSDs is usually hardly noticeable. Even using SATA II does not have much of an effect.
If you can get a Samsung non pro at the right price, then it's a very good option. I've compared an 840 250gb non pro to an 840 Evo 250gb in my own PC. Despite the Evo having better specs (especially write speed), I really can't tell any difference. The Evo might be a smidge quicker booting up and a tiny bit more responsive, but that's probably me wanting to believe that it is. Yes, if I were to copy a very large file to the non-pro, or a lot of smaller files, I would probably notice that it takes a second or two (or even more) longer. For the amount of times I do that, it's not worth worrying about. I would have thought that I'd notice a difference when installing software (or even Windows itself), but I can't say that there is any difference.
The truth is that for the vast majority of users, any modern SSD is going to be fast and probably as reliable as a mechanical drive. If you want to search for the best specifications, by all means do so, but it is unlikely that you'll notice any difference between decent SSDs. You may as well look around for an SSD at a good price, and for a make/model with a decent reputation. Samsung and Crucial are the two brands that I`ve mainly used, and both have been 100% reliable and all of their SSDs go like mud off a shovel.